Rug up for rain and chilly South

Temperatures have taken a dive today as a cold southerly sweeps over the country.

Sizzling summer days in the mid-30s and restless nights kept awake by a humid 20C will seem like a distant memory as temperatures fall to the teens and overnight lows hit single digits.

Those in the lower South Island might want to wear an extra layer of clothing, with the forecast high in Queenstown today only hitting 13C and dropping to a shivering 3C tonight.

Cardrona skifield near Queenstown got a dusting of snow this morning and posted a photo on its Facebook site.

Dunedin this morning was sitting on just over 11C - a big drop from the 35C recorded a month ago - and isn't expected to get over 20C until Tuesday.

Rain's also forecast for Oamaru, Wanaka and Invercargill with a high of just 14C, while Greymouth will be a little warmer, reaching 18C.

Christchurch isn't much better, with a high of 15C forecast and an overnight low of 8C.

🌧️Rain is on the way for the upper South Island and lower North Island tonight into Sunday.🌧️This will be the best chance for rain in quite a while in Nelson, although amounts of 5-10 mm will be the best-case scenario.🌧️Heavy rain may effect Kaikoura and Wellington-Wairarapa. pic.twitter.com/ULcHWbrKd4— NIWA Weather (@NiwaWeather) February 22, 2019

Much of the lower North including Wellington, Palmerston North and New Plymouth will sit in the mid to high teens through the day, with Palmerston North set to get as low as 5C tomorrow night.

While the top of the north, including Whangarei, Auckland, Hamilton and Tauranga are still sitting in the low 20s during the day, overnight lows are expected to get down to 7C in Hamilton and 11C in Auckland - a big change from those sticky humid nights a few weeks back.

Strong winds and "plenty of rain" is also set to hit eastern parts of both islands today, with heavy rain watches forecast overnight in Hawkes Bay, Waipara, and Canterbury foothills, and continuing through much of Sunday.

The heaviest falls are expected about the Kaikoura Coast and Ranges, where a warning is in force. Expect 70 to 90mm of rain to accumulate, possibly up to 120mm in localised places.

MetService meteorologist Stephen Glassey said 65mm of rain has fallen in the area since 4pm yesterday - with a lot of that since midnight.The warning is in place until 1pm today, but lighter showers are expected to continue afterwards and into tomorrow.

Overnight Porters Pass and Methven received the most rain, with 70mm recorded.

WeatherWatch also reported today's southerly winds will be made stronger and colder by a large high in the Tasman Sea. Glassey said strong southerly winds were being felt in the Cook Strait as well as eastern parts of central New Zealand.

Cyclone Oma is "definitely not" heading to New Zealand and the tropical air which has fuelled it, creating a drizzly nuisance across the North Island this weekend, is set to dissipate today.

WeatherWatch said Oma is trapped in the Coral Sea for the coming week, remaining "well away from New Zealand", as it heads back north potentially towards New Caledonia.

MetService meteorologist Rob Kerr said by late Monday or early Tuesday this week, another high pressure ridge will push off the wet southerly winds creating fine conditions.

🌧️Rain is on the way for the upper South Island and lower North Island tonight into Sunday.🌧️This will be the best chance for rain in quite a while in Nelson, although amounts of 5-10 mm will be the best-case scenario.🌧️Heavy rain may effect Kaikoura and Wellington-Wairarapa. pic.twitter.com/ULcHWbrKd4— NIWA Weather (@NiwaWeather) February 22, 2019